The present invention relates to electrical lampholders and, in particular, to a lampholder having a cantilevered center contact.
The center contact of a lampholder for an electric lamp should provide a reliable current path from the lampholder to the eyelet of the lamp base. The contact itself should have low resistance and there should be low resistance between the contact and the lamp eyelet. In addition, the contact should provide and maintain an adequate contact force between the contact and the eyelet. The contact (and lampholder) should also not degrade at temperatures up to 200 degrees Centigrade.
Mogul lampholders (and larger) have difficulty in providing all of the above functionality with a single element contact structure. Historically these contacts have been formed from nickel plated brass, or other good conductors, backed by a coil spring. The contact material provides the desired electrical properties and the coil spring provides the desired springing contact force.
Recent mogul lampholders have employed a single element cantilevered spring steel contact structure. Such contacts may consist of stainless steel type 302. These contacts have not proven to be entirely satisfactory. In many cases, these contacts have either burned up themselves and/or burned up the lamp eyelet. These failures have been exacerbated by higher wattage lamps (e.g., 400 watts and greater).
A lampholder for an electric lamp includes an insulating socket, a circumferential contact located inside the socket and a cantilevered contact. The cantilevered contact has a first end and a second end, where the first end is attached to the socket and the second end is adapted to make springing electrical contact with the lamp. The cantilevered contact is formed from a spring-like material and has a lamp contacting portion composed of a material having an electrical resistance less than that of the spring-like material.